Chemical process



May 29, 1945. w. F. ROLLMAN 2,377,107

CHEMICAL PROCESS Filed Nov. l5, 1941 2 Sheets-Sheet 2 W 5%@ .y/amwwm Patented May 29, 1945 l 'CHEMICAL raocEss Walter F. Rollman, Cranford, N. J., assignor, by mesne assignments, to'Jasco, Incorporated, a corporation of Louisiana Application November 15, 1941, Serial No. 419,303 1 claim.' (o1.A 19e- 52) The present invention relates to a method of treating hydrocarbons, and in particular, it rlates to a method for renning petroleum for the purpose of producing good yields of high octane number motor gasoline.

In carrying my invention into eect, I charge a crude petroleum oil to a fractionating column and I fractionate it into a plurality of separate cuts or fractions, including a light naphtha, a heavy naphtha, a Wide cut gas oil, and a residuum representing approximatelyl 20% bottoms on thel total crude. Of course, the foregoing manner of fractionating the original crude petroleum oil is merely illustrative of my process and other cuts or fractions may be obtained from the original crude. In particular, the Width oi' the naphtha cuts or fractions, that is to say the boiling range of the same, may be varied as a means of controlling the composite gasoline octane number, mean value or level, as will more fully appear hereinafter. I then subject the various fractions, except the light naphtha to separate treatments as follows: reform the heavy naphtha, catalytically crack the gas oil and coke the residuum, polyinerize the unsaturates from the coking operation and then combine the products thus formed which boil in the gasoline range to recover from the process maximum quantities of high.' octane gasoline.

In order to afford a better understanding ci my invention, reference is had to the accompanying drawings which show diagrammatically a iicw plan indicating my improved method or" processing a crude oil.

Referring in. detail to the drawings, a crude petroleum oil is introduced into the system in line i and thence discharged into a furnace t Where it is heated to a temperature o1", say, about '75th Zi. and thence withdrawn through line 5 and discharged into the fractionating column l. Sevn erai cuts or fractions are recovered from the fractionating column as follows: A light naphtha is Withdrawn overhead through line i and delivered to a stabilizer i i for blending with other gasoline produced in the process, as will more fully appear hereinafter. A heavy naphtha is withdrawn from the iractionating column 'i through line it, discharged into a furnace i5 where it is heated to a temperature of. say, 900 F., thence withdrawn through line it and discharged into a catalytic fixed bed hydroforming reactor it containing a hydroforming catalyst, such as an aluminachromia catalyst or other known hydroforming catalyst, where said heavy naphtha is reformed in the presence of hydrogen in a manner known to the art. This operation is carried out preferably at a temperature within the'range from about 880 F. to 980 F., at a pressure of from 10D-600 lbs./sq. in. gauge, and at a feed rate of 0.3 to 2.0 volumes of liquid naphtha/reactor volume/hour. Approximately G-5000 cu. ft. of the butanefree gas, i. e., containing C3, Cz, and C1 hydrocarbons as Well as hydrogen, produced in the process, per barrel of oil is recycled through line 29 for the purpose of maintaining the desired hydrogen concentration in the reaction zone.

Instead of catalytically hydroforming thenaphtha, it may be reformed thermally to improve the quality of the naphtha. This may be a coil-only operation thus obyiating the necessity for using reactor 20 since the reforming operation may be performed in coil it.

The reformed naphtha is withdrawn from reactor 20 or from coil l5 through line 2i and thence discharged into a separation drum 2t from which gasoline is taken overhead through line 2t and delivered to a stabilizer 2t. An aromatic low gravity polymer is withdrawn through line 30 from the bottom of the separation drum it and sent to fuel oil storage tank i013). The Cr hydrocarbons produced in hydroiorming are highly saturated and hence are not readily susceptibie to subsequent polymerization to hydrocarbons in the gasoline boiling range. In the process here in cuestion, hydroformed gasoline including the C4 cut is withdrav'm through line i227, the included hutane heing used to provide the necessary volatility. in the final blend of gasoline produced from the several steps in the combination of processes. Butane-free gas from the hydroforming process is -rented overhead through line 2t, from the stabiliner it, with the exception of the gas which is recycled through line 29 for the purpose of maintaining the necessary hydrogen concentration in the hydroforrning reactor.

Referring hach to fractionating column l, a second cut comprising a wide boiling range gas oil is Withdrawn through line t2, heated in the l furnace iii to a temperature of say 900 F., thence withdrawn. through line il and mixed with a powdered catalyst, such as an acid treated clay, the catalyst being obtained from a supply source il@ through line di and dispersed or suspended in the gas oil vapors in line 3i. The dispersion ci catalyst in oil is then passed through a reactor where the gas oil undergoes cracking in av system represented generally by til. The equipment for carrying out this step or stage of my process may be such as that shown, for example, in the application of Eger V. Murphree et al., Serial No.

371,923, filed December 22, 1940, or any other suitable system in which a gas oil is catalytically cracked in a continuous operation in the presence of a powdered catalyst. The cracked vapors are recovered from the catalytic cracking system through line 52 and after separation' of the catalyst by a suitable device or devices, such as cyclone separators and/or Cottrell precipitators..

the vapors are discharged into a fractionating column 56. High boiling cycle stock is recovered from fractionator 55 through line 02, and this oil is mixed with the bottoms from fractionatlng column 1 as will subsequently appear, to be discharged into a coking vessel 11. Heating oil of say '100 F. E. P. is recovered from fractionating column 55 through line 60 and delivered to a suitable` storage vessel 65, to be sold as. such or it may be recycled for further gasoline production if desired. Gasoline and gas are taken overhead from fractionator 50 through line 51 and delivered together with the light naphtha from line to stabilizer Debutanized gasoline is withdrawn through line |2 from stabilizer and delivered to gasoline accumulator |0| where it is blended with gasoline from other steps in the process as will be shown hereinafter. Gases including butane are taken overhead from stabilizer through line ||0 and delivered to fractionator ||2 from which C3 and C4 hydrocarbons are taken o the bottom through line Ill and lighter gas, i. e., C1 and C2 hydrocarbons, withdrawn overhead through line IIE. The C3 and C4 hydrocarbons produced in catalytic cracking contain appreciable quantities of unsaturates suitable for catalytical polymerization to hydrocarbons in the gasoline boiling range, as will be shown hereinafter.

Referring again to fractlonator l, residuum (about 20% to 30% oi' the crude) is withdrawn through line and mixed with catalytic gas oil bottoms in line 02, as previously indicated, and

then discharged into a furnace 10 where it is heated to a temperature oi' say 800 17k-900 F., whereupon the mixture is discharged through line 16 into a coklng vessel '|'|,v preferably of the down-flow type although other types may be used, where it is converted to coke, gasoline and lighter hydrocarbons. The residuum is coked in drum 'ill at conditions of high temperatures and short contact or residence time within the colsing zone, say l0 to 15 seconds, such as are described in the application oi Walter F. Rollman, Serial No.v

ffl-03,822, led July 24, i941, these conditions being especially suitable for the production of high yields of high octane gasoline from the reslduum. The necessary high temperature, namely, say,

ll|l00 F. to 1500" F. prevailing in. colting drum lll is obtained as the sensible heat of swam produced in furnace 05 from water in line 00 and introduced into the coking drum through line 0). Other gaseous mediums, such as ethane, methane, nue gas, etc., may be used although steam is preferred. The steam is superheated to a temperature of from l500 F. to i800 F. and ows countercurrently upward against the down-nowlng oil through the colring drum 1l. The poking drum itself is maintained preferably at a pressure of from about 0 to 150' lbs/sq. in. gauge. The more volatile products of the coking operation containing gasoline and lighter hydrocarbons are withdrawn through line 90, thence discharged into a separator 02.

From separation drum 02, a fuel oil is withdrawn from the bottom thereof through line 90 and discharged into line 80 for eventual discharge into fuel oil receiver or accumulator |00, where it is mixed with the hydroiormed polymer as mentioned above. Under certain conditions it may be desirable to return this stock to line 1li for further coking. It is pointed out that in coking drum 11 among the products obtained are gasoline and lighter hydrocarbons and a very low gravity fuel oil, with substantially no gas oil formed. Therefore, the overhead product in line 96 which leads to fractionator 98 contains, as stated, gasoline, C4 hydrocarbons and lighter hydrocarbons, and, of course, steam. Debutanized gasoline is Vwithdrawn from fractionator 08 through line |01 and is discharged into accumulator |0| where it is mixed with gasoline produced elsewhere in the process, as will be shown` hereinafter. Water is withdrawn thru line |05. 'Gases produced in the coking process, including C4 hydrocarbons, aretaken overhead from fractionator 98 thru line |20 and discharged to secondary fractionator |04 from which propane-free gases are vented overhead thru line |03, and Ca and Ci hydrocarbons are withdrawn from the bottom of the fractionator thru line |06. The C3 and Ci. hydrocarbons are highly unsaturated, and the C4 cut contains material quantities of butadiene, which is recovered as such in butadiene recovery unit |25. 'I'his equipment, as is true of the other equipment described herein, is shown quite schematically in theow plan. Butadiene is withdrawn through line |21 and collected in accumulator |29. The remaining C2 and C4 hydrocarbons produced in the coking process, freed of butadiene, are withdrawn from the butadiene recovery unit through line |30.

The above-mentioned butadiene-free Cs and C4 hydrocarbons produced in the coking process are mixed with the Ca and C4 hydrocarbons from the catalytic cracking process. rI'he resulting blend thus comprises all the hydrocarbons of this type produced in the combination of processes, with the exception of the highly saturated C4 produced in hydroforming and included in the gasoline withdrawn from that process (line 21). The mixture is discharged into furnace itl where it is heated toa temperature suitable for catalytic polymerization and thence discharged into a polymerization unit |35 containing catalyst and operating preferably under a pressure in the neighborhood of 100 lbs/sq. in. The unsatura'd hydrocarbons present in the feed to the polymer unit are thereby polymerized to hydrocarbons the gasoline boiling range. it is understood, oi course, that necessary provisions for recycling through the polymerization unit and for the Withdrawal of saturated unpolynierizable hydrocarbons from the system although not shown in be schematic now plan, are to be understood and included as part or the unit. The polymeriaed product is withdrawn from the polymerization unit through line ill@ and delivered to gasoline storage ibi where it is mixed with other essonne produced in the combination of processes. The gasoline in storage iti may be ther reed by treatment with acid, doctor solution, clay and the like, to give a ilnished gasoline. Tetraethyl lead may also be added to improve the cote-ne number still further.

The above described combination is obviously quite flexible both as to product quality and yields, but it is contemplated that in its preferred form the combination of processes will be so adjusted that when including catalytic polymer gasoline and the saturated C4. from the hydroformer, little if any excess Cs is produced over 10 lbs. R. l?. P.

gasoline. In other words, the gasoline produced will be essentially 10 lb. R. V. P. gasoline with no excess butane. I'he following yields and product quality were obtained from an East Texas crude when operating under the preferred procedure:

Gasoline (10# R. V. P.) -vol. per cent.- 60.0 Heating oil (31 A. P. I.) do- 17.2 Fuel oil (8.6 A. Pi I.) do 9.4 Butane-free gas weight per cent-- 11.2 Cokef. do 1.9 Butadiene dn 0.25 Gasolineoctane number (C. F. R.) 90.8

Y The high yield and octane number of the gasoline obtainable by this combination of processes is notable. Under other operating conditions the heating oil and fuel oil may be further processed to yield lighter products and coke. y While I have set forth certain details hereinbefore, obviously numerous modifications of my into a fractionation zone, recovering a light naphtha from said .fractionation zone, catalytically hydroiorming said heavy naphtha. recovering a gas oil from the fractionation zene, catalytically cracking said gas oil to produce catalytically cracked gasoline, 4C: and C4 unsaturated hydrocarbons and high boiling cycle stock, recovering a heavy residual ,oil from said fractionation zone, mixing the high boiling cycle stock recovered from they catalytic cracking zone with the heavy residual oil, coking said mixture at temperatures in the range of from about 1000 F. to 1500 F., in the presence of added steam, permitting the oil to remain in the coking zone for a period of from Iabout 10 to l5 seconds, recovering coke still gasoline from said coking zone, recovering butadiene from the C4 hydrocarbons produced in the coking step, catalytically polymerizing unsaturated Ca and C4 hydrocarbons produced in the catalytic cracking step and remaining after recovery of butadiene from the C4 hydrocarbons and blending together the light naphtha, the hydroformed naphtha, catalytically cracked gasoline, coke still gasoline, and catalytic polymer.

WALTER. F. ROLLMAN. 

